Acute corneal edema decades after penetrating keratoplasty for keratoconus in eyes wearing scleral contact lenses

Scleral lenses for correction of irregular astigmatism: advances and limitations

PURPOSE OF REVIEW

In this review, we will address advances and limitations in the field of scleral lenses pertaining to the correction of irregular astigmatism.

RECENT FINDINGS

There are reports on the benefits of scleral lenses for eyes with irregular astigmatism, particularly regarding improvement of visual acuity and the reduction of higher-order aberrations. Innovations such as wavefront-optimized and wavefront-guided optics can improve vision in keratoconus. Customized haptics, topographic and profilometric-based fitting, and impression-based design can achieve fit in problematic eyes with ectasia, after penetrating keratoplasty, and with corneal scarring. Challenges persist, including resource requirements for practitioners, patient difficulty with insertion and removal, and limitations to lens wear, including midday fogging and corneal edema. Risks such as graft failure persist.

SUMMARY

Scleral lenses have emerged as a useful tool in the management of irregular astigmatism, reducing the need for penetrating keratoplasty. By vaulting the cornea and resting on the sclera, scleral lenses neutralize corneal astigmatism, while providing a stable and comfortable surface for advanced optics. Over the past two decades, the use of scleral lenses has increased, reflecting advances in fitting systems, expanded access, greater adoption by clinicians, broader patient eligibility, and improved clinical outcomes.

Contact lenses for visual rehabilitation in post-keratoplasty eyes: A systematic review

PURPOSE

To evaluate the role of contact lenses (CLs) in visual rehabilitation following keratoplasty.

METHODS

Four databases, including PubMed, Scopus, Web of Science, and Embase were systematically searched for studies published between January 2010 and July 2023. Visual outcomes, daily wearing duration, subjective comfort, rate and etiology of CL discontinuation, corneal endothelial cell density, central corneal thickness, and complications were extracted.

RESULTS

This review included thirteen case series and two chart reviews, analyzing a total of 464 eyes, of which 97% underwent penetrating keratoplasty. Scleral CLs were the most frequently fitted lens (285 eyes, 61%). All studies reported a significant improvement in visual acuity with CL correction. Most post-keratoplasty patients could wear CLs comfortably for 8 to 12 h/day. The rate of CL dropout ranged from 0% to 39%, mainly due to CL intolerance, discomfort, and graft rejection. Corneal graft rejection (18 eyes), conjunctival hyperemia (8 eyes), corneal epithelial trauma (5 eyes), graft edema (4 eyes), and microbial keratitis (3 eyes) were the most frequently reported complications.

CONCLUSION

CLs are effective for improving visual acuity following keratoplasty, with minor complications depending on the type of CL.

Contact lenses for visual rehabilitation in post-keratoplasty eyes: A review

To assess the role of various types of contact lenses (CL) after penetrating and lamellar keratoplasty, we reviewed all studies that were related to CL fitting in post-keratoplasty (full-thickness and lamellar) eyes between 1990 and 2024 by using relevant search keywords. The demographic data, indications for CL fitting, duration between keratoplasty and CL fitting, CL design and fitting methodologies, refractive outcomes, topographic and biomechanical changes, aberrometry, specular microscopy, corneal thickness, graft survival, and complications were analyzed. A total of 32 original studies and seven case reports were evaluated. All studies showed favorable refractive outcomes. Complications, if any, were managed successfully with conservative treatment and temporary discontinuation of lens wear. Most authors preferred to use large-diameter multicurve rigid-gas permeable lenses and scleral lenses over hydrogels and hybrid or piggy-back varieties, with an inclination toward late fitting due to multiple factors. The lenses did not have any adverse effect on graft survival. CLs are a useful tool in post-keratoplasty visual rehabilitation. However, patients require meticulous workup, a thorough fitting methodology, attention to associated problems, and close follow-up to monitor for complications.

Contact lens fenestrations and channels in relation to tear exchange and corneal oedema

Oxygen delivery and tear exchange are considered essential to maintain corneal homoeostasis during contact lens wear. Since the 1940s, fenestrations and back surface channels have been utilised in scleral, corneal rigid, and soft contact lenses in an attempt to enhance corneal oxygen transmission, facilitate the removal of carbon dioxide from the post-lens tear layer, minimise corneal oedema and prevent post-lens tear stagnation. This review examines the use of contact lens fenestrations and channels in both clinical and laboratory settings, and the effect of these modifications upon tear exchange and corneal oedema. Despite almost a century of modifying contact lenses to alter tear dynamics and promote corneal health, the evidence regarding the efficacy of fenestrations and channels is mixed.

Acute Corneal Edema in a Middle-Aged Patient

A middle-aged patient who had bilateral penetrating keratoplasty 20 years ago for keratoconus presented with pain and blurriness of the right eye for 2 days. Despite prompt corticosteroid therapy, they had no vision improvement and reported occasional pain. What would you do next?

Characterisation of ectasia after penetrating keratoplasty in keratoconus eyes using anterior segment optical coherence tomography

BACKGROUND/AIMS

Ectasia of the cornea can occur decades after penetrating keratoplasty (PK), especially in keratoconus eyes. The purpose of this study was to characterise ectasia after PK by morphological findings in anterior segment optical coherence tomography (AS-OCT).

METHODS

In this retrospective, single-centre case series, 50 eyes of 32 patients with a history of PK at an average of 25±10 years earlier were included. The eyes were classified either as ectatic (n=35) or as non-ectatic (n=15). The main parameters included central corneal thickness (CCT), lowest corneal thickness at the interface (LCTI), anterior chamber depth, graft-host interface angle at the thinnest point and host cornea-iris angle. Furthermore, steep and flat keratometry readings obtained by AS-OCT (CASIA-2, Tomey) and Scheimpflug tomography (Pentacam, Oculus) were assessed. OCT findings were correlated with clinical grading of ectasia.

RESULTS

There was a highly significant difference in LCTI, graft-host interface angle and anterior chamber depth (in pseudophakic eyes) between the groups. The ratio calculated by the quotient of LCTI divided by CCT was significantly lower in ectatic than non-ectatic eyes (p<0.001). In eyes with an LCTI/CCT ratio of ≤0.7, the OR for the occurrence of a clinical detectable ectasia was 2.4 (CI 1.5 to 3.7). Steep keratometry values were significantly higher in ectatic eyes.

CONCLUSION

AS-OCT is a helpful tool to recognise and quantify ectasia in post-PK eyes objectively.

High Astigmatism Secondary to Peripheral Ectasia Recurrence in Postpenetrating Keratoplasty Eyes Managed With Miniscleral Contact Lenses

OBJECTIVES

After penetrating keratoplasty (PK) for keratoconus, vision can be impaired by high-degree astigmatism, particularly in those patients with recurrent peripheral ectasia. Scleral contact lenses (CLs) have long been used in the management of keratoconus both in treatment-naive corneas and those postcorneal transplants. We report the use of miniscleral CLs and their related visual and clinical outcomes in a series of patients with post-PK peripheral rim ectasia.

METHODS

In this retrospective case series, 5 patients (7 eyes) presented because of reduced visual acuity with their spectacles/CLs and/or reduced comfort with their existing rigid gas-permeable lenses. All patients in this series underwent PK more than two decades ago for keratoconus (mean 28.7 years±7.2). All patients demonstrated characteristic thinning at the graft-host junction, with anterior chamber deepening. Central corneas had remained clear in all patients inferring high visual potential. Contact lenses used were No 7 Comfort 15 miniscleral and the Onefit MED scleral with 14.5 mm and 15.6 mm diameters, respectively.

RESULTS

All eyes achieved a best-corrected visual acuity of 6/9 or greater. One case had difficulty with insertion and removal and has since discontinued wearing lens at this time. All others are successfully wearing the lenses regularly.

CONCLUSION

Despite advances in CL design, surgical management is still required in some patients. Miniscleral CLs are effective in the refractive management of peripheral ectasia in keratoconic post-PK eyes and should be considered in such eyes before proceeding with repeat surgical intervention.

Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets

"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.